City lost 2-1 to a late Amad Diallo winner for the visitors, leaving the hosts now with just one victory in 11 games.
“It is something we are missing,” said Guardiola afterwards.
“When you win games, the energy is higher. This is my job. My job is not just to win games and lift trophies.
“I am incredibly well paid to handle these situations. Maybe in one year or a year and a half we were able to lose eight games - now in one month and 10 days we have lost eight games out of 11.
“We were top of the league and the only unbeaten team in Europe (before this run).
“We are a big club; I am here because of what we have done in the past. Otherwise clubs would not sustain their manager.
“All the managers around the world work harder and think more and talk more. I have to tell them that still we are so good.
“I knew it would be a tough season, even when we were winning, but I didn’t expect it to be so hard like it is right now.”